问题 选择题

以下能用光的反射来解释的现象是(  )

A.树荫下的光斑

B.海市蜃楼

C.岸边的树在湖中的倒影

D.一端插入水中的筷子看起来变弯折

答案

A、树荫下的光斑是由于小孔成像形成的,因此属于光沿直线传播现象;

B、海市蜃楼是由于空气的不均匀导致光线发生弯折形成的,因此属于光的折射现象;

C、树在水中的倒影属于平面镜成像现象,因此树在水中倒影属于光的反射现象;

D、水中的筷子看起来变弯折,是由于来自筷子的光从水中进入空气中发生了折射,折射光线进入人眼,人眼逆着光线看去,所看到的是筷子的虚像,像比物体位置高,属于光的折射.

故选 C.

单项选择题
完形填空

Recently I was invited to a friend’s house for supper—and had a meal I have never had before.

All the friends invited were a little surprised. It’s not that Ben is unsociable, or a bad cook, but it’s just that he never 21more than he has to. So how come he was inviting us round for a meal? Had he bought something 22for his friends? He greeted us at the door and showed us into his dining room where a 23_ -table was waiting for us.“Nothing but the best for my friends!”said Ben. We all sat down and looked 24 at each other—what was he up to?

Ben returned with four bowls of hot soup.“It’s a mixture of carrots, potatoes and tomatoes,”said Ben. The next 25was also a little strange in that we didn’t quite know what it was again. It’s just another mixture of vegetable.

As we ate we chatted and finally the 26 turned back to what we were eating.“Was there a recipe(食谱) for this,”asked Marina,“or did you 27 it up?”Ben put his fork down.“What I cooked depended on what I could find.”Marina was surprised.“But you can find anything in supermarkets these days.”“But there’s 28 choice in what you can find outside supermarkets,”he replied.

Seeing that we had all finished the food, Ben decided to tell the truth. He had read recently that supermarkets usually throw away 5 percent of their food every day. So Ben decided to look inside his local supermarket bins. There he found food that was slightly out of __29, boxes of throw-away vegetables and fruit.

So Ben had successfully provided a decent(体面的) meal for his friends, and made us aware of the fact that there are many poor people who need the food, but the amount of food thrown away is enough to 30 millions of people.

21.A.takes  B. spends   C. uses D. does

22.A.cheap  B. special  C. practical    D. usual

23.A.new    B. separate C. booked   D. laid

24.A.nervously  B. carefully    C. sadly    D. happily

25.A.course B. food C. soup D. salad

26.A.dinner B. idea C. food D. subject

27.A.pick   B. look C. make D. take

28.A.less   B. more C. some D. any

29.A.order  B. place    C. season   D. date

30.A.enrich B. please   C. affect   D. feed